This has been driving me nuts for quite sometime.
I have a Windows 98 pc with Oracle installed, as well as sql server and interbase (I have had the problem also with each individually).
Whenever I start or connect to a database, directly or via an application, my dialup networking activates, and I need to cancel it. After that the database access proceeds fine.
This is quite bothersome.
I have tried uninstalling and reinstalling my dialup networking which someone suggested may change the order that the software looks for the database, but it did not help.
My address is email@example.com if you have any ideas, though please post them here for general benefit as well.